The Morchella genus contains the species that make up the true morels. This name comes from "morchel", a word from old German meaning mushroom.
The true morels are renowned for their distinctive appearance and unique taste. Thus hunting for them (and eating them!) has grown into a sport of its own.
Yet despite their popularity, mycologists still have many questions about these mushrooms. What is the true number of species in the genus? How exactly do they feed? What conditions are needed for the mycelia to produce mushrooms?
Let's take a closer look at some of the science behind the true morels. We'll begin by looking at types of morels, then move on to reproduction and life cycle, and end with an oft debated question: mycorrhizal or saptrotrophic?
So just how many species of true morels are there in the genus Morchella? If you were hoping for a straight answer I'm sorry to disappoint. The truth is that nobody knows.
Some mycologists insist there are only three species; others say there are over 50. The problem arises when we try to define what a species truly is. Do we group mushrooms by physical characteristics? DNA evidence only? What about geographical location and other traits?
As the term species is a human concept, there's bound to be disagreement over how organisms should be classified. Until we know how many species actually exist in the Morchella genus, most people divide true morels into three informal groups:
Depending on where you live, you may hear about other informal groups such as greys, whites, or reds. These vary from place to place and are often just off-colored variations of the black, half-free, or yellow.
Studies are ongoing to determine the true number of species in the genus Morchella. To read about one such study see the Morel Data Collection Project.
True morels are ascocarps, meaning they belong to the Phylum known as Ascomycota. These are the largest phylum of fungi, commonly called "sac fungi" due to their bowl-like shapes. Other types include lichens, cup fungi, truffles, and most yeasts.
Ascocarps are defined by their asci, the sex cells of the fungus that bear spores. Each ascus usually houses eight ascospores. Eight spores may not seem like a lot, but keep in mind the average morel has millions of asci!
Take a look at this wonderful picture, a close up of the asci of a black morel. Note the eight spores.
The morel life cycle is roughly as follows:
This is a simplified view of a precise process. Environmental conditions must be just right for the sclerotia to form mushrooms.
As if Morchella science wasn't divided enough, here's one more question: How do these mushrooms feed? Are they saprotrophic or mycorrhizal?
The evidence for morels as mycorrhizal fungi is strong. As they're often found near certain types of trees such as elm and apple, mycologists believe they form relationships with the roots of these trees. They are also notoriously difficult to impossible to cultivate in a lab.
However, they also display saprotrophic qualities. The trees they're found near are often dead or dying, and their mycelium colonizes dead organic material quickly.
More research is needed before the true Morchella place in nature is revealed. It is now widely accepted that morels can play the role of both saprotroph and mycorrhizal partner.
So many different variables come together to create the mysterious morel! As science and amateur observation moves forward, so will our understanding of this prized mushroom.
The picture of morel asci was taken by Peter G. Werner and is published on Wikipedia under the GNU Free Documentation License.